What does "counterlath" mean?

Counterlath: (a) A batten laid lengthwise between two rafters to afford a bearing for laths laid crosswise. (b) Any lath laid without actual measurement between two gauged laths. (c) Any of a series of laths nailed to the timbers to raise the sheet lathing above their surface to afford a key for plastering. (d) One of many laths used in preparing one side of a partition or framed wall, when the other side has been covered in and finished.